Enlargement effect of the crucible size on Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub y/ single crystals grown by a modified vertical Bridgman method

Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub y/ (Bi-2212) superconducting single crystals were prepared by a modified vertical Bridgman method using large alumina crucibles of a 26 mm bore diameter with cone-shaped bottom. In order to obtain large and high quality single crystals, we optimized growth conditions using the large crucibles. We obtained a large plate-like single crystal with a size of 17.0 mm /spl times/ 5.5 mm when the crystal growth was carried out with the rotation speed of 50 rpm and at the temperature for starting the crystal growth of 1000/spl deg/C. In the single crystal, the FWHM value of the (0010) x-ray diffraction peak which was assigned to a Bi-2212 superconductor was small and about 0.06/spl deg/. T/sub c/ of the single crystal was about 87 K, which was higher than T/sub c/=82 K of the single crystals grown with smaller crucibles whose bore diameter is 35% less than the large crucibles.